Thermostats have long been used to control HVAC systems. Such thermostats are typically mounted flush on a wall in the space or zone that is being heated or air conditioned at approximately five feet of height from the floor. Aesthetic considerations exert a major influence on the design of thermostats that are to be used in occupied zones and spaces, including homes and office spaces. For such uses, it is desirable that the thermostat be as unobtrusive as possible. A principle consideration is that the thermostat project from the mount on the wall into the space as little as possible. From the standpoint of acceptance in the marketplace, a thermostat having a minimal profile, as measured between the wall on which the thermostat is mounted and the outer surface of the cover, is much preferred over a thick thermostat the provides the same functional capabilities.
A minimal profile thermostat has both functional and safety advantages, as well as being aesthetically pleasing. For instance, such a thermostat is less likely to be accidentally bumped by traffic in the room in which the thermostat is installed. The impact of such inadvertent contact may be enough to dislodge the thermostat from its mount on the wall or to dislodge the cover from the subbase.
More particularly, thermostats typically have the cover and subbase formed from a polymeric material. Both the cover and the sub-base have electronic components affixed thereto that must be electrically connected when the cover is engaged to the subbase. There are also mechanical connectors that cooperatively engage to mate the cover to the subbase. The mechanical connectors between the cover and the subbase are typically formed integral to the cover and subbase during the formation process and are therefore made of the same material. Such material is a very serviceable material under ordinary conditions, but may not have the strength to be able to withstand the force of a sharp blow. Such a blow may break the mechanical connectors, preventing the cover from being reconnected to the subbase or pull the anchors from the wall on which the thermostat is mounted and pull out the electrical connections from the thermostat to the HVAC system. Additionally, the electrical connections may be disturbed by such a blow, rendering the operator controls that are typically mounted on the cover inoperable.
All of the above described consequences of an impact to a protruding thermostat result in the thermostat being at least temporarily inoperable. An inoperable thermostat can have serious consequences, especially during spells of extreme cold. Since the heating unit of the building is controlled by the thermostat, an inoperable thermostat usually results in the loss of all heat to the building. During such spells, HVAC repair personnel are typically overtaxed and it might be several days before a failed thermostat can be repaired.
Thermostats typically have a connecting block affixed to the subbase. The connecting block is utilized to connect the wires from the HVAC system to the thermostat. During installation, the wires from the HVAC system are brought through an opening in the subbase and the subbase is then mounted on the wall. The wires are then connected to the connecting block. The majority of the electronic components of the thermostat are typically affixed to the cover. This facilitates the ready removal and installation of the cover onto the subbase without disturbing the wire connections.
Currently, thermostats having electronic components in generally two opposed portions of the thermostat to be mated together as described above are designed to be mated in the plane that is perpendicular to the plane of the opposed portions. This usually results in the subbase being firmly affixed to the wall. The opposed portion is then positioned spaced apart from the subbase and aligned therewith. A pushing motion toward the wall on which the subbase is mounted and perpendicular to the plane of the subbase, coupled with a relatively firm force is required to simultaneously engage the opposed portion and the subbase both mechanically and electrically. In such thermostats, the electrical connectors and the mechanical connectors are oriented to engage in a plane that is perpendicular to the wall on which the thermostat is mounted. Such orientation contributes substantially to the overall profile of the thermostat.
The thermostat that is the subject of U.S. Pat. No. 5,107,918 is typical of the current designs. The '918 device has a subbase, an opposed portion, and a hinged cover. The cover does not have any electronic devices incorporated therein. The electrical communication means and the mechanical coupling means are designed to be engaged with cooperating electrical communication means and mechanical coupling means formed in the opposing portion by the above described procedure.
The electrical communication means of the '918 device are typical of electrical connectors that are utilized in such applications. As depicted, the electrical communication means are: relatively long and are oriented in a plane that is perpendicular to the plane of the subbase. With such orientation, the profile of the thermostat is affected by the length of the electrical communication means. At one extreme, the profile absolutely can be no more narrow than the length of the electrical communication means. Practically, the thermostat must have a substantially greater depth of profile than the length of the electrical communication means in order to accommodate the other components of the thermostat that are aligned with the electrical communication means and are interposed between the subbase and the cover.
It would be a decided advantage in the HVAC industry to have a thermostat having a minimal profile. The advantage would evidence itself in appeal to the consumer as well as in the areas of functionality and safety. The minimum profile thermostat should be easily mounted on a plane surface, such as a wall, and it should provide for easy assembly and disassembly of the major components of the thermostat, such as the cover and subbase.